Nick Turse, "The Pentagon Book Club," Nation, 29 April, reviews Mark Philip Bradley's Vietnam at War, John Prados's Vietnam: The History of an Unwinnable War, 1945-1975, Lewis Sorley's A Better War: The Unexamined Victories and Final Tragedy of America's Last Years in Vietnam, and Sorley's Vietnam Chronicles: The Abrams Tapes, 1968-1972.